1. Field of the Invention
The present invention relates to a device for transferring power by electrical energy transformer, and in particular by magnetic coupler, and more particularly such a device comprising on a primary side a primary winding in series with an alternating source and on a secondary side a secondary winding, a rectifier bridge and a load.
2. Description of the Related Art
These devices exhibit, in general, two major drawbacks.
Firstly, magnetic couplers have poor efficiencies owing to the physical separation of their primary and secondary windings. This poor efficiency is due more particularly to a considerable leakage inductance which makes the known structures, for example of the flyback or forward type, unusable.
Moreover, the devices of the known type also exhibit the drawback that regulation thereof does not generally enable them to be implemented simply by bringing the primary and secondary windings closer together.
The present invention aims to alleviate these drawbacks.
Accordingly, the subject of the invention is a device for transferring power by electrical energy transformer, and in particular by magnetic coupler, comprising on a primary side a primary winding in series with an alternating source and on a secondary side a secondary winding, a rectifier bridge and a load, characterized in that the rectifier bridge comprises two diodes arranged in a known manner in series with the secondary winding and two MOS transistors also in series with the secondary winding, the load being connected on the one hand to the point common to the two diodes and on the other hand to the point common to the two MOS transistors, means being provided for switching the said transistors in such a way that they are simultaneously in the on state for a predetermined duration.
It will be seen that such a layout amounts to short-circuiting the supply to the primary onto the leakage inductance. The high value of this inductance is thus harnessed for use as storage inductance. In the invention, this high value of the leakage inductance therefore no longer constitutes a drawback.
Advantageously, the said means are provided for switching the said MOS transistors in such a way that the said duration occurs while the two diodes are off.
There is therefore no transfer of energy to the load during the storage phase in the leakage inductance.
Furthermore, the device can then be regulated by determining the duration of the storage phase as a function of the desired output current.
Regulation is thus performed solely at the secondary. The device can thus be put into service simply by bringing the primary and secondary windings physically closer together.
A particular embodiment of the invention will now be described by way of non-limiting example with reference to the appended drawings in which: